1. Field of the Invention
The present invention relates to a lens driving device that is mounted in a mobile apparatus, a mobile phone, or a lens barrel of a camera and that is used as an autofocus lens module.
2. Description of the Related Art
Japanese Registered Utility Model No. 3124292 describes an existing technology in this field. A lens driving device according to this utility model includes a fixed frame having a bottom lid and an upper lid. Support portions stand at four corners of the bottom lid, and the upper lid is disposed more inward than the support portions. Magnets are fixed to four corners of the fixed frame. A movable unit including a lens holder is disposed in the fixed frame, and a lens and a coil are fixed to the lens holder. A helical spring that urges the movable unit in one direction is disposed in the fixed frame, and the movable unit is disposed inside the helical spring. In such a lens driving device, the movable unit moves toward one end of the fixed frame against the urging force of the helical spring when the coil of the movable unit is energized. The movable unit is retained at the other end of the fixed frame due to the urging force of the helical spring when the coil is in a de-energized state. (See also Japanese Unexamined Patent Application Publication No. 2007-139810.)